A method for improving the spatial resolution of frontside-illuminated CCD's
Abstract
A method is proposed for improving the spatial resolution of frontside-illuminated silicon CCD imagers. The technique involves building the device on an epitaxial layer deposited on a more highly doped substrate of the same conductivity type, creating a high-low junction. A simple theoretical model for the carrier diffusion limited modulation transfer function (MTF) is developed for this structure. Calculations of the MTF using this model are compared to similar calculations for other configurations, e.g., a thinned, backside-illuminated device and a frontside-illuminated imager built on a uniformly doped substrate. The calculations show that the new structure has MTF performance comparable to or better than the backside-illuminated device and has, for a wavelength of 1.06 microns and Nyquist spatial frequency, an MTF which is nearly an order of magnitude higher than that for the nonepitaxial frontside-illuminated device.
- Publication:
-
IEEE Transactions on Electron Devices
- Pub Date:
- March 1981
- DOI:
- 10.1109/T-ED.1981.20323
- Bibcode:
- 1981ITED...28..251B
- Keywords:
-
- Charge Coupled Devices;
- Image Transducers;
- Modulation Transfer Function;
- Semiconductor Junctions;
- Spatial Resolution;
- Doped Crystals;
- Epitaxy;
- Imaging Techniques;
- Minority Carriers;
- N-Type Semiconductors;
- Quantum Efficiency;
- Instrumentation and Photography